Intestinal parasitism in the marine iguana

What is it?

Intestinal parasitism in the marine iguana is the presence of roundworms (nematodes), flatworms (cestodes), or protozoa (single-celled organisms) living in its digestive tract at the animal's expense.

This condition is very common in reptiles, even in the wild, because they live in constant contact with soil, feces, and natural parasitic flora. In the marine iguana, an endemic species of the Galápagos Islands that feeds mainly on marine algae, some parasites are part of its normal digestive ecosystem and may even help it digest plant material.

Problems arise mainly when this balance is disrupted: stress, captivity, unsuitable diet, or excessive parasite burden. The parasite then shifts from a simple "tenant" to an actual cause of disease.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

Parasitism is caused by different groups of intestinal parasites: nematodes (roundworms, including pinworms which are very common in iguanas generally), cestodes (flatworms), and protozoa such as coccidia or certain flagellates.

These parasites are transmitted mainly by fecal-oral route: the animal ingests eggs or cysts present on algae, rocks, or in water contaminated by infected feces. In the wild, this constant exposure allows a relatively stable balance between host and parasite.

Several factors promote the shift from asymptomatic carrier status to declared parasitic disease: stress (handling, transport, captivity), unsuitable temperature or humidity that weakens natural defenses, poor diet lacking algae or unsuited to the species' specific needs, overcrowding in a confined space, and an immune system already weakened by another illness.

Young individuals and recently captured or relocated animals are particularly vulnerable.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

Treatment, when deemed necessary by the veterinarian, relies on antiparasitic medications appropriate to the type of parasite identified (deworming agents for roundworms or tapeworms, antiprotozoan drugs for coccidians or flagellates).

Support treatment may be added: rehydration, nutritional support, correction of environmental conditions. It is essential never to treat without a prior diagnosis, as mild parasitism that the animal tolerates well does not always require treatment, and inappropriate medication can disrupt the animal's natural digestive balance.

Prevention

Possible complications

A heavy parasite load that goes untreated can lead to severe dehydration, significant weight loss, intestinal blockage in rare cases of heavy worm infestation, or general weakness making the animal more vulnerable to other infections.

In young animals, lasting growth delay is possible.

When to see a veterinarian

Prognosis

The prognosis is generally good when parasitism is detected and managed early, with appropriate treatment and improved living conditions.

It becomes more guarded in cases of heavy infestation, delayed treatment, or general weakness already present, particularly in young animals.

Frequently asked questions

References

WOAH — Organisation mondiale de la santé animale (ex-OIE)

Content reviewed by the TunisieVet editorial team · Updated 09 September 2026